This invention relates to a simplified clutch mechanism for providing capacity modulation in a scroll compressor through a simplified arrangement.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor a pair of scroll members each include a base with a generally spiral wrap extending from the base. The wraps interfit to define compression chambers. One of the two wraps is caused to orbit relative to the other, and the compression chambers decrease in volume. One limitation on scroll compressors is that the orbital direction must be in a single direction of movement. Thus, if the orbiting movement is caused by driveshaft rotation in a forward direction the scroll compressor will operate properly. On the other hand, if the shaft should be driven in a reverse direction such that the scroll member orbits in a reverse direction the results would be undesirable. For this reason, it has generally been a goal of scroll compressor designers to eliminate any occurrence of rotation in a so-called reverse direction.
One other goal of compressor designers is to provide the ability to change, or modulate, the capacity of the compressor. One method of achieving capacity modulation is to vary the amount or volume of refrigerant being compressed.
Compressors have been proposed wherein clutch mechanisms including planetary drives are positioned between the drive motor and the orbiting scroll. When the drive motor is driven in a first direction the orbiting scroll is caused to orbit in a forward direction. However, when the motor is driven in an opposed direction the shaft passes through the planetary transmission such that a distinct speed in a forward direction is achieved. By providing the two different speeds, capacity modulation is achieved. Moreover, the planetary drive and the clutch mechanisms are arranged such that the drive to the orbiting scroll causes the orbiting scroll to orbit in a forward direction regardless of the rotation direction of the motor. While these proposed arrangements show promise, they are somewhat complicated.
In the disclosed embodiment of this invention, the driveshaft of a scroll compressor motor extends along a driveshaft into a first one way clutch. If the driveshaft and clutch are driven in a first forward direction then the clutch passes this rotation along to the mechanism for driving the orbiting scroll directly. Thus, during normal operation the driveshaft is driven in the forward direction and the one-way clutch passes the rotation on to the mechanism for driving the orbiting scroll. The scroll compressor operates in a normal fashion.
A counter-gear is engaged with a gear on the driveshaft xe2x80x9cupstreamxe2x80x9d of the one-way clutch on the driveshaft. The counter-gear is caused to rotate in an opposed direction to that of the driveshaft. A countershaft is driven by the counter-gear. Thus, when the driveshaft is driven in the forward direction, the counter-gear is driven in an opposed direction. A one-way clutch is positioned on the countershaft and serves to not pass rotation from a first countershaft portion to a second countershaft portion when the driveshaft is driven in the forward direction. The second countershaft portion drives another counter gear which is preferably engaged with an idler gear, and which further drives another gear on a second driveshaft portion which is downstream of the first one-way clutch.
Now, when the motor is driven in a forward direction, drive passes through the first one-way clutch and directly to the mechanism for driving an orbiting scroll. The countershaft is driven in a reverse direction and the first countershaft portion rotates in that direction. When driven in a reverse direction, the second one-way clutch allows slipping movement, and thus the second countershaft portion is not driven by the first countershaft portion. Instead, the downstream gear on the main driveshaft drives the idler gear and the second countershaft portion. However, the second one-way clutch accommodates the relative rotation of the first and second countershaft portions.
When the motor is driven in a reverse direction, then the first one-way clutch does not drive the first and second driveshaft portions together, but instead allows slippage. In this case, the counter-gear and thus the first countershaft portion are now driven in a forward direction. This in turn causes the second countershaft portion to be driven through the second one-way clutch by the first countershaft portion. Drive then passes through the idler gear back to the driveshaft and eventually to the orbiting scroll in a proper forward direction. The gear ratios of the several gears can be controlled to achieve desired capacity modulation when the motor is driven in the two directions.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.